The Matryoshka Dollhouse

This one I did not expect.

The Tardis lands in the titular toy-shop and the crew find themselves amongst giant teddy bears, model trains with cars that are large enough for the Doctor to sit in, and oversized Erector Sets. Despite hailing from the mid-18th century, Jamie is well-versed in 20th century Christmas rituals as he wonders aloud if they are in the Toy Department of Harridges at Christmas, the property room of a theatre at pantomime time, or perhaps in Santa Claus' workshop at the North Pole.

While the story begins in a light-hearted manner, it soon takes a turn for the weird. Something like Doctor Who crossed with House of Leaves.

They stumble upon a rather large dollhouse - life-sized - and wander inside. The Doctor goes upstairs and finds a room with a dollhouse that is a scale model of the same one he's in. Somehow he enters that one and becomes trapped in a Matryoshka dollhouse nightmare. He isn't sure how he manages to do it, but he manages to enter a series of dollhouses nested inside other dollhouses.

At one point, he comes across a dollhouse that emanates incredibly bright light a la Kiss Me Deadly. Upon entering another one, he hears strange noises.

He gets so lost, so racked with fear, that he begins to sob.

Now aside from this very un-Doctorlike sobbing, this is a wonderfully strange little tale. One of the most uncanny Doctor Who stories I've ever come across.